A National City Resident Tested His Faucet’s Yellowing Water, Here’s What He Said
National City resident Ramel Wallace wanted to know what was in the apple juice-stained water that ran from his faucet earlier this month, so he tested it and sent me the results.
Although a water quality test purchased at Walmart isn’t as detailed as one performed by a hydrology specialist in a lab, Wallace’s tests didn’t seem to show anything out of the ordinary, said Justin Brazil, director of water quality at Sweetwater, after hearing the results are read to him by a reporter.
The pH (water acidity) of National City well water is around 7.8, Brazil said. Its hardness (a measure of dissolved minerals, specifically dissolved calcium and magnesium) is between 170 and 180 parts per million, which is quite hard. Wallace’s test results seemed to match these parameters.
But Sweetwater Authority, which treats and sells drinking water in National City, Bonita and much of Chula Vista, didn’t actually test the water when it turned yellow a few weeks ago.
“It’s very, very well characterized,” Brazil said. “That’s why we didn’t carry out any additional tests. And by the time we did field surveys, the water was already clearing up.
What he means is that it happens enough at Sweetwater Authority for Brazil to be convinced of what caused it. This yellowed water, Brazil reiterated, is a product of the natural iron and manganese minerals that settle and sit at the bottom of water pipes. They are some of the most abundant minerals in the earth’s crust, Brazil said, and are therefore found in aquatic systems.
The Sweetwater Authority is unique to San Diego because it draws approximately 70% of its water from local sources, such as the Sweetwater River which originates in the Cuyamaca Mountains and empties into the Pacific Ocean, and groundwater from drawn wells in aquifers. But the rest of San Diego County gets most of its drinking water from the Colorado River.
Most Sweetwater customers travel by gravity from these mountains, but when there is an unexpected increase in water pressure, such as a broken fire hydrant or an open main water valve (which caused the latest incident of sepia-stained tap water), all of these minerals again become mixed with the water and appear at the tap.
“It’s a bit like a snow globe,” Brazil said. “This snow will stay at the bottom of the snow globe all the time, but if you shake it momentarily, everything becomes suspended and eventually calms down.”
The incident that affected Wallace’s water happened right on the border of an area that receives water by gravity and another area where water is pumped to higher elevations and stored in tanks. This high pressure rushed into this low pressure area and bam, a snow globe rattled.
The Sweetwater Authority began a process to flush these minerals from its pipes in 2019, but the COVID-19 pandemic has slowed progress, Sweetwater Authority spokeswoman Leslie Payne said. Typically, water line flushing means that water is pumped out of a fire hydrant and lost to a storm drain, which is a pretty big waste of drinking water. Sweetwater therefore hopes to try a new circular process where water is discharged through a filtration device mounted on a truck.
“This will significantly reduce the number of future water quality complaints in National City,” Payne said.